The print quality is not good

This is usually due to a bad drum or fuser, maybe the transfer belt on a color laser. Every time I've seen this (including my failing C3326, I am running until I exhaust the remaining toner, at which point I will be moving to a C3426 or CS431 as I couldn't find a nice CS521), I've never seen a bad belt outside of units abused in a corporate setting. It tends to be a bad drum.

Note regarding the belt: That being said, I usually do not see belts fail unless the PC is super high. That's the ONLY TIME I have seen it besides abuse to the belt (with one exception: OLDER color lasers where it's a wear item due to the manufacturers struggling to make the belts last 200-250k+ pages).

This one will be more complex to isolate, given you have a drum and transfer belt configuration with a color laser. To ensure it isn't the fuser, do a halfway test where you pull the printed page out of the unit before it can go to the fuser; if it doesn't produce the same fault, you have a bad fuser. If the same issue occurs before you get to the fuser, it's likely the imaging drum (Samsung was the last one to put out color lasers with atrocious drum yields for colors and shared one drum between color and black. As a result, the rated lifetimes (16k black/4k color) were ALWAYS slashed to need a new drum at the low end before the drums gave out.

This is one of the reasons I was never fond of Samsung lasers from the beginning: Other manufacturers like Lexmark and Xerox with split drum and toner setups (HP and Canon used to be exclusively combo drum+toner at this time) had printers with 100-125k page drums or used their brain and split the drums piecemeal, such as in the Xerox designed color Phasers with the lower yield part such as the 6510 (4x 48k page drums, individually installed); the Lexmark models of this era (CSX10/X17) series were running 125k page combined CMYK drums for crying out loud!

If the drum is bad, I do not know if you can still buy them (given that HP bought the Samsung printer division and used the same engines in their printers, including their many weak points) for cost reduction reasons (which remains a non-issue with Canon engine HPs like the CP and color Pro 400 series). The issue is HP wasn't interested in making the Samsung CRUM ID supplies outside of ones they had to commit to keep in production for legal reasons, so it may be a hard find since this is an engine HP abandoned being so horrible. If you can find them OEM, the Samsung part number is SU403A or CLT-R406 (may differ under HP ownership; look at the "replaces" on HP Samsung consumables to make sure).

I tried to find it in the HP US store, but they no longer sell it on the HP site directly but I did find it in the HP Canada store. It uses the same CLT-R406 part number thankfully. Buy this anywhere else but HP, given I still see them on sites like Amazon; even OEM.

HP Canada

If you replace the imaging drum and isolate the fuser, the transfer belt will need to be replaced. Unlike higher-end color printers (Ex, C3326, MC3326, C3426, and CS series), there's no way to adjust the color registration directly on the printer; it may have a fully automatic option in "tech mode." I've never seen a cheap Samsung with full-blown adjustment options. You will need the Samsung service software to fix everything; unless you can find this and a new transfer belt, you will probably need to replace the printer. Don't buy an HP; they're DRM garbage with the lowest end using Samsung engines (which are cheap junk). The current lineup with the Canon engine is just as bulletproof as the pre-2016 DS junk, but they ruined it with the HP DS firmware. Your best bet these days is a Canon Color ImageCLASS.